Characters Move Independently In Single Text Object
Image above showing extents of individual characters in a single Blender Text Object.

Some miscellaneous points.


For ease of expressiveness, in the not quite so long run, I suggest you animate either single letter text objects or the mesh converted objects.
You may want to search for a script which already does what you want.
Text can follow path as a whole quite easily.  Having each character follow a different path requires more work.  Link for various approaches ...How-To: Text Sliding out of a Circle 2D
Your statements lead me to believe you want characters following individual paths.






In the image above we see the Blender Python Console window.  We have probed the location and dimension of a text object.  You see the X-axis value increase as I add letters.  Subtraction required for individual character location perhaps other considerations.  I have not found a more abstract probe for individual substrings of a larger string.






In the image above is a text editor window with an executed script.  The blue balls have been placed at right side x axis of each letter.  Thus the script has some reasonable knowledge of extents in the x direction.  You can store the measurements in a Python list if that suits you.
Inspect, Verify and Improve the script.
Know that text character placement may not be as easy as placing a cube.  Text characters have their own sense of orientation and aesthetics.  Baseline for example.  If you separate characters of a text object take care to notice any adjustments to the individual origins.  
If you have final placement of the single objects whether text or mesh you can keyframe those positions as final positions.  Then your animation can occur close enough to those final positions.  For example a path which gets close enough to your final position can ease out its influence.
There is more left for you to discover.